Update mtdna_backend.py

mtdna_backend.py

@@ -280,13 +280,19 @@ def summarize_results(accession):
         # ✅ Open the known_samples sheet
         spreadsheet = client.open("known_samples")
         sheet = spreadsheet.sheet1
-    
+        required_columns = [
+            "Sample ID", "Predicted Country", "Country Explanation",
+            "Predicted Sample Type", "Sample Type Explanation",
+            "Sources", "Query_cost", "Time cost"
+        ]
+        
         # ✅ Read old data
         existing_data = sheet.get_all_values()
-        if existing_data:
+        if existing_data and existing_data[0] == required_columns:
             df_old = pd.DataFrame(existing_data[1:], columns=existing_data[0])
         else:
-            df_old = pd.DataFrame(columns=df_new.columns)
+            df_old = pd.DataFrame(columns=required_columns)
+
     
         # ✅ Set index and update old values with new ones
         df_old.set_index("Sample ID", inplace=True)